When Christ’s word doesn’t agree with our idea, we immediately conclude that it must mean something else. After all, our idea is right!

But Peter said to him, “Explain this parable to us.”
Matthew 15:15 NET

In chapter 13 Jesus explained everything to the crowds by parables, without which he taught nothing. Now, the Lord makes a clear and direct statement. Peter, however, doesn’t understand it, because it contradicts everything that he has learned. He thinks that, if it disagrees with his opinion, it must then be a parable, with a meaning besides the obvious.

This is why he asks the Lord to explain the “parable,” when it is no such thing.

We do the same. When Christ’s word doesn’t fit our theology, it then must be a figure of speech, or limited to that age, or an insertion by later disciples and therefore not genuine.